P-toluene sulphonic acid

The sulphonation of toluene at 100-120° results in the formation of p-toluene-sulphonic acid as the chief product, accompanied by small amounts of the ortho and meta isomers these are easily removed by crystallisation in the presence of sodium chloride. Sulphonation of naphthalene at about 160° 3uelds largely the p-sulphonic acid at lower temperatures (0-60°) the a-siil-phonic acid is produced almost exclusively. 

A number of basic materials such as hydroxides, hydrides and amides of alkaline and alkaline earth metals and metal oxides such as zinc oxide and antimony oxide are useful catalysts for the reaction. Acid ester-exchange catalysts such as boric acid, p-toluene sulphonic acid and zinc chloride are less... 

Toluene-2,6-di isocyanate p-Toluene sulphonic acid o-Toluidine... 

The effect of the catalyst-steroid ratio has been studied for the p-toluene-sulphonic acid-catalyzed ketalization of androst-4-ene-3,17-dione. Selective formation of the 3-monoketal is observed with the use of an equimolar amount of ethylene glycol and a low ratio of catalyst to steroid. ... 

Oxidation of malonic acid by Cr(VI) has been noted briefly by Snethlage and later by Kemp and Waters . The kinetics are simple second-order but the acidity dependence is complex. Heckner et a/. find the alkaline permanganate oxidation of malonic acid (and also of o- and p-toluic acids and of p-toluene-sulphonic acid) to be retarded by added Mn(VI), viz. 

The availability of Nafion on silica has not only lowered the cost of the resin but also has made it versatile (Sun et al., 1997 Harmer et al., 1998). A number of industrially important reactions have been attempted, with considerable success, with these catalysts. Consider the Fries rearrangement of phenyl acetate to p-acetyl phenol (/t-hydroxy acetophenone). This has been accomplished by Hoelderich and co-workers (Heidekum, 1998). In the ca.se of alkylation of benzene with benzyl alcohol, Amberlyst-15 and p-toluene sulphonic acid are ineffective and Nafion on silica works well at 80 °C. 

Gonzalez and Holt (1981) have shown how macrocyclic lactones can be made conveniently in microemulsion media. Thus, intramolecular e.sterification of (o-hydroxy alkanoic acids can be carried out with a very small amount of acid catalysts like p-toluene sulphonic acid, and rates are markedly higher as compared to simple media. 

A trade-off between selectivity and solvability should be considered when selecting a solvent. Adding co-solvents can make tough separations technically and economically feasible. Lee and Gentry (1997) have tabulated dielectric constants of selected solvents. A new class of solvents is based on the use of an aqueous. solution of hydrotropes. Gaikar and Sharma (1989) have reported the separation of close-boiling p-cresol and 2,6-xylenol with aqueous solutions of hydrotropes, such as the sodium salt of p-toluene sulphonic acid, as a novel solvent in extractive distillation. 

Polymeric adsorbents have also been found to be very useful, and even highly water-loving undesired materials like p-toluene sulphonic acid from waste streams can be recovered via ad.sorption and regeneration with solvents like fv -propanol. In such instances, the regeneration of activated carbons is not satisfactory, even with aqueous sodium hydroxide. Solutes like phenols, substituted phenols, aromatic amines, heterocyclic amines (pyridine, picolines, etc.) can be recovered, in a rewarding way, from aqueous solutions. 

From a preparative aspect, Peck et alX have employed the counter-current distribution technique with a partition system of water/ butanol/p-toluene sulphonic acid to separate and purify the neamine (neomycin A) present in commercial neomycin. 

The water formed in the reaction is continuously removed from the reaction mixture by azeotropic distillation, in order to avoid reversible reaction between water and ester. The progress of reaction can be followed either by measuring the amount of water or by determining the amount of unreacted acid in aliquots withdrawn at regular intervals of time. The reaction can be carried out either in presence of a catalyst, i.e. a weak acid like p-toluene sulphonic acid (a strong acid can hydrolyse the polymer, formed) or in absence of the catalyst. 

Catalyst Ion exchanger with DVB content (%) p-toluene- sulphonic acid... 

M. R. Jenner and R. Khan, Use of dimethoxydiphenylsilane, AI,AI-dimethylfonnamide, and toluene-p-toluene sulphonic acid as a novel acetalating reagent, J. Chem. Soc. Chem. Common. 30 (1980). 

Dihydrocarvone [l] was treated with isopropenyl acetate in the presence of p-toluene sulphonic acid and converted into a mixture of enol acetates [2] and [3], separated by GLC Treatment of [2] with boron trifluoride in methylene chloride at room temperature for 10 minutes gave (+) Camphor [U]. This synthesis is particularly interesting in that it is a chemical analogy for the biosynthesis conversion of a monocyclic into a bi-cyclic monoterpenoid. 

Furthermore, salicylamide could be characterized through the formation of diphenylmethyl derivative prepared by refluxing with diphenylmethanol and p-toluene sulphonic acid in acetic acid (8)... 

Acetylamino-p-toluene sulphonic acid amide Cyclohexylamine... 

Indanyl)-phenol 16 was obtained by reacting p-methoxy-phenyl-acetic acid ethyl ester with benzylchloride to form a-benzyl-p-methoxyphenyl ethyl acetate, saponification into the acid, conversion of the acid with thionylchloride into the chloride, cyclization to 2-p-methoxy-phenyl-l-indanone, NaBH4 reduction to 2-p-methoxyphenyl-l-indanole, dehydration with p-toluene-sulphonic acid in toluene to 2-p-methoxyphenyl-indene, catalytic hydrogenation to 2-p-methoxyphenyl-indene, and treating the ether with HBr [Eq. (5)]. 

Oligomeric benzil ketals (DTGPA), prepared by reaction of 2,2-dimethoxy-2-phenyl-acetophenone (DMPA) with triethyleneglycol, in the presence of p-toluen-sulphonic acid, are reported [88] to be efficient in the UV curing of styrene/ unsaturated polyester formulations giving rise to coatings with very low odour. 

Despite the numerous polyesters described in the literature, it is only recently that the cyclic populations of ring-chain equilibrates of linear aliphatic polyesters have been characterised. This characterisation was based on the well-known investigations of Carothers 121, 122) and his co-workers and the studies of Billmeyer 123-125) and his group. In particular, Billmeyer s wodc established tetraisopropyltitanate as a catalyst for producing equilibrium between ring and chain molecules in polyester systems. This is in contrast to the catalyst, p-toluene sulphonic acid, used by Jacobson, Beckmann and Stockmayer 127) in what was effectively the first attempt to study experimentally and theoretically the change in the total cyclic population of... 

In carrying out the reaction to produce the compound of formula 11 above, temperature and pressure are not critical and this reaction can be carried out at room temperature and atmospheric pressure. If desired, lower or elevated temperatures can be utilized. This condensation reaction is advantageously effected at a temperature of from about 0° C. to about 120° C. In a preferred embodiment of this invention, the reaction is particularly preferably carried out in the presence of p-toluene-sulphonic acid in benzene by heating to a temperature of about 80° C. for 2 hours under reflux conditions. 

A mixture of 2.2 g. (20 mMol) of crystalline resorcinol, 3.05 g. (20 mMol) (+)- ra/is-/j-menthadien-(2,8)-ol-(l) and 0.4 g. (2 mMol) of p-toluene sulphonic acid monohydrate in 50 mL. of benzene is heated under reflux for 2 hours. The resulting solution is dissolved in 50 mL. of diethyl ether. The ether is extracted once with dilute sodium bicarbonate solution. The ether phase is dried and evaporated. 5.1 g. of a yellow oil is obtained. This oil is chromatographed on 250 g. of silica gel and eluded with benzene. After distilling off the benzene under high vacuum, there is obtained 778 mg. of (-)-l-hydroxy-6,6,9-trimethyl-6a,10a- rans-6a,7,10,10a-tetrahydrodibenzo(b,d)-pyran. This compound has an RF value (silica gel thin layer chromatogram in chloroform) of 0.35 and a boiling point of 155°C./0.001 mmHg. 

It must be assumed that higher [l,m,n]-eliminations (m n, m > 2, n S 2) can be found and developed in a large variety of ways. The synthetic potential of those types can be indicated with some examples Thus, the thermal conversion of 202 to 204 (48%)113) can be reasonably formulated via initial [l,3,4]-elimination of hydrogen chloride to produce the intermediate bicyclobutane 203 which is stabilized by a [1,2/2, -rearrangement. The base-induced reaction of 205 (55%) leads to the displacement of p-toluene-sulphonic acid and to the migration of the inner chain bond 114). Therefore, it must be classified as [l,3,(2)4]-elimination. The dehydroxy-silylation of 207 to 208 (20%)115) is typical for [l,4,(3)2]-eliminations (migration of the Se—C-chain bond). 

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